Thanks for the suggestions.
They are not traditional bolts and nuts, they are actually plumbing hardware, and the “nut” is some type of cap.
I don’t want to do anything permanent, because I may have to move them elsewhere. I may have to figure out how to drill a hole in the cap so I can use some sort of cotter-pin.
Have you tried teflon tape yet? You may have to adjust how many wraps to get it to stay where you want.
I’m sure I could suggest a great alternative or solution but I can’t quite envision what I’m working with.
Fit a ball bearing into the gear hole…should reduce overall friction and should prevent any nuts from getting tight or lose.
best I can think of is to double nut it unless its a pipe cap then in that case a cross drill and pin and a dab of lube on the face that touches the gear
Oooooh!
I want one for my kids. 
I think I’ll design some and put up in our family room.
Safe to assume not cut on a laser?(unless really big bed). Very kewl to have in the house - what a conversation piece and the gears are so ornate (as opposed to simple toothed circles). Nice job
Actually, they were all cut on a laser with a bed size of 12x24 (slightly bigger than GF).
The largest gear is made of 28 pieces that were glued together.
All of those gears could be cut on a glowforge.
One of the things that’s hard to wrap one’s brain around (at least for me) is the notion that it’s possible to cut mating pieces out with a laser, allowing for kerf, and have them just. fit. If I cut something by hand, I’m lucky to get within 1mm (at least on the initial pass). If I 3D-print something, maybe a quarter of that (allowing for surface texture, rounding of corners and warpage). I’m looking forward to being able to design stuff where multiple parts fit reliably.
Same here - after struggling with this K40, seems like kerf is always too wide…(Granted it’s user error most likely, which is why I want the GF;s user-friendly interface so badly)
Kerf will be nothing compared to my clumsy measurements and technique when using saws. 